I'm having a similar problem with a Stanley Fat Max utility knife I bought a couple of weeks ago. It has a tendency to lose the blade making heavy cuts in drywall. Very frustrating when the blade comes out of the knife for no reason while in use. :kamahlitu
Just as a general rule, I don't think I'd buy a knife at the dollar store. :nah: I have two knives that I use on a regular basis. A hunting knife from Dick's Sports and the Kobalt utility knife. I've noticed that on the Kobalt, sometimes the blade slips out when I'm cutting drywall, but only because I'm putting pressure on the blade release thing. :BangHead::BangHead::BangHead: The solution is to keep the pressure on the handle. :icon_thum
I had a Lennox front load utility knife that I got from the orange borg. At first I loved it. But soon found out that the blade loved to come out when cutting drywall. It was too much of a pita trying to remember I had to hold it just so... Chucked it, actually a pair of them.
Now I have a pair of them that have a big gold knob on the side that allows for easy access to change blades. I got sick of having to try and find a screw driver, or walking back to the van to get a screw driver to get inside of the old stanley style knives. The new knife has an offset bend in the middle of the handle to facilitate added leverage when needed. LOVE IT!!